The Eye of Timaeus and Dark Magician Girl (First, you need to clearly distinguish the text meanings of the cards)
The Dark Magician deck has a different way of combining effects than most other decks today. Instead of the cards being linked together through the common part on the card name frame (which is the archetype name), these cards support each other through the card text box below.
More specifically, these cards will refer to the Dark Magician monster itself in the card text (main monster).
You also need to clearly distinguish between cards that refer to Dark Magician monsters themselves or cards that only refer to monsters of the Dark Magician card race.
The card that is different from the rest of the set is The Eye of Timaeus , in the text of this card it requires targeting 1 “Dark Magician” monster which means you can target both Dark Magician or Dark Magician Girl , not just Dark Magician monster. Because of this, most of the other cards that support this deck cannot interact with The Eye of Timaeus .
Another example to help you visualize more easily, in the text of the Dark Magician Girl monster, this monster gains 300 ATK for each Dark Magician in the graveyard . The text only says "Dark Magician" and not "Dark Magician". The monster is referring to the original Dark Magician monster. If there are Dark Magician Girls in the grave, Dark Magician Girls on the field will not increase ATK for them. each of these monsters.